Transcript NOISE

Dr.Malik Muhammad Abdul Razzaq
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Dr. Malik Muhammad Abdul
Razzaq
Assistant Professor
 Department of Community Medicine
 Sheikh Zayed Medical College
 Rahim Yar Khan
Dr.Malik Muhammad Abdul Razzaq
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 Noise
is often defined as “unwanted sound”,
 Noise is wrong sound in the wrong place, at the wrong
time.
 Noise has become a very important “stress factor”
 Normal conversation produces a noise of 60-65 dB
 Whispering, 20-30 dB;
 Heavy street traffic 60-80 dB;
 Boiler factories about 120 dB;
 Normal tolerable limit is 85 dB;
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Noise has two important properties:
Loudness
Loudness depends upon the amplitude of the vibrations
which initiated the noise. The loudness of noise is
measured in decibels (dB).
 Frequency:
The frequency is denoted as Hertz (Hz.) One Hz is equal
to one wave per second. The human ear can hear
frequencies from about 20 to 20000 Hz. This range is
reduced with age and other subjective factos. Many
animals (e.g., dogs) can hear sounds inaudible to the
human ear.

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To signify the vast cacophony of sounds
that are being produced in the modern
life, are leading to health hazards.
These hazardous effects are:
1.
Auditory effects
2.
Non-Auditory effects
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a. Auditory Fatigue:
 It
appear in the 90 dB region and greatest at
4000 Hz.
b. Deafness:
 The
hearing loss may be temporary or
permanent. Repeated or continuous exposure to
noise around 100 decibels may result in a
permanent hearing loss.
c. Occupational hearing loss:
 When
there is exposure to noise above than 100
dB the result is hearing loss. Exposure to noise
above 160 dB may rupture the tympanic
membrane and cause permanent loss of hearing.
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
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
Interference with speech
Annoyance
Efficiency
Physiological changes
Economic loss
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 CAREFUL
PLANNING OF CITIES
 CONTROL OF VEHICLES
 BUILDING ACOUSTIC INSULATION
 INDUSTRIES AND RAILWAYS
 PROTECTION OF EXPOSED PERSON BY
USING EAR PLUGS, etc.
 LEGISLATION
 EDUCATION
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RADIATION
Radiation is part of man’s environment.
 SOURCES:
 The sources of radiation are man – made and natural
 Natural
Man – Made
 1. Cosmic rays
1. Medical and dental Xrays, Radioisotopes
 2. Environmental:
2. Occupational
exposure

a. Terrestrial
3. Nuclear:

b. Atmospheric
radioactive fallout
 3. Internal:
4. Miscellaneous:

Potassium-40
 Carbon – 14

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Dr.Malik Muhammad Abdul Razzaq
Television sets
radioactive dial
Watches, Isotope tagged
products,
Luminous markers.
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 1.
IONIZING RADIATION:
 Is applied to radiation which has the ability to
penetrate tissues and deposit its energy within
them. Ionizing radiation may be divided in to
two groups:
 Electromagnetic radiations e.g., X- rays and
gamma rays,
 Corpuscular radiations e.g., alpha particles and
beta particles (electrons) and protons.
 Cosmic rays also contain ionizing radiations
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These are electromagnetic radiations of
wavelength longer than those of ionizing
radiation. All non-ionizing form of
radiations have less energy than cosmic,
gamma, and X-radiation.
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 Roentgen:
Roentgen is the unit of exposure. It is now
replaced by Coulomb per kilogram
 Rad:
Is the unit of absorbed dose. It is now
replaced by SI units as Gray
 Rem:
Is the product of the absorbed dose and
the modifying factors. The Rem indicates
the degree of potential danger to health.
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1. SOMATIC EFFEXTS
 A dose of 400 to 500 roentgens on the whole body is
fatal.
 Immediate effects:
 Radiation sickness
 Acute radiation syndrome
 Delayed effects:
 i. Leukemia
 ii. Carcinogenesis
 iii.Foetal developmental abnormalities
 iv. Shortening of life
2. GENETIC
 Chromosome mutations
 Point mutations
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1. Avoiding Exposure to X-ray:
Of the man – made sources, a dose of 4 rad is delivered
a part of body when exposed to X-ray in about one
minute. So unnecessary X-ray examination should be
avoided in children and pregnant women.
2. Lead aprons:
.5mm of lead apron will reduce the intensity of
scattered X-ray over 90 per cent. Workers must wear a
film badge or dosimeter which shows accumulated
exposure to radiation.
3. Safe operation of nuclear power plants and
enunciating the basic principles of radiation
protection.
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